Building DAC with lineout and headphone out

I'm making a DAC using a DIYINHK AK4493EQ (768kHz/32Bit AK4493EQ DAC BARE PCB, I2S/DSD input - DIYINHK). It sounds great right now with the lineout. I've probably committed a sin and have wired up headphones directly to the lineout and run at cut volume.

I have dual +-12V (could up to 15V too) rails using a variety of op-amps (opa2134, ad8620, etc.). I haven't been rolling op-amps yet.

What's the recommendation for adding a headphone amp or headphone out? I have a lineout going to a tube amp currently that I am very happy with. I'd like to add a headphone out.

I'd ideally solve for low-impedance IEMs (massdrop plus universal IEMs) as well as higher impedance cans.

Should I go with a single pole 4 throw setup and switch between two lines? If the single op-amp is able to drive sufficient volume
 
The OPA1622 adapter boards without a real ground pin will produce more distortion than a properly connected OPA1622. It may be possible to run a short length ground wire from the OPA16322 ground pin to mainboard ground. One guy did that and measured considerably less distortion. Ummm...using a resistor voltage divider between the power pins as an approximate ground is not really the best solution, IMHO.